2 injection wells shut down after Oklahoma quakes

Oil and gas operators shut down two wastewater injection wells in northern Oklahoma and reduced operations at a third after several earthquakes centered in the town of Crescent rattled the state.
Stephens Production and Devon Energy each voluntarily closed one well, and Stephens reduced operations at another well by 50 per cent, Oklahoma Corporation Commissioner Matt Skinner said.
"In this case, we didn't have to issue a directive. We simply called them up and said what we were looking at," Skinner said yesterday. "In terms of fast cooperation from the industry, there's always exceptions to the rule, but broadly speaking we've had very fine cooperation."

Crescent is a town of about 1,400 people that's about 35 miles north of Oklahoma City. Earthquakes in the area recorded by the US Geological Survey include a magnitude 4.5 quake at 1:12 pm on Monday that is the strongest reported in the state so far this year.
In all, more than 15 temblors of magnitude 2.0 or stronger were reported Monday by the Oklahoma Geological Survey. An additional nine quakes ranging from 2.2 to 4.1 were recorded through early yesterday evening.
There were no immediate reports of injuries or damage in the area, although people reported feeling the 4.5 quake as far as 650 miles away in Indiana and Minnesota, according to the USGS.

The Oklahoma Corporation Commission, which regulates the oil and gas industry in the state, recently announced plans to place more than 200 disposal wells under scrutiny as it investigates whether injecting wastewater deep underground is triggering earthquakes.

An Oklahoma Geological Survey report in April said it was "very likely" the practice prompted most of the state's recent earthquakes.
The quakes are occurring along a fault line that extends for about 50 miles across Logan County, which is north of the Oklahoma City area, Austin Holland, seismologist for the Oklahoma Geological Survey, said.
"It's a good-size fault," Holland said. "And we are certainly looking at a greater potential for a larger earthquake.

"The likelihood of a significant earthquake has increased based on what we understand about earthquake scaling relationships and our increased rate of seismicity."
The largest recorded earthquake in Oklahoma history was a 5.6 earthquake centered near the town of Prague in November 2011.